256 COLtTBBID^. 



a. Seven upper labials ; portion of rostral visible from above 



not more than Half as long as its distance from the 

 frontal. 



a. Ventrals 103-148. 



Scales in 15 rows ; Buboaudals 65-94 .... 2. vernalis, p.' 258. 

 Scales in 13 rows ; subeaudals 51-64 .... 3. agassizii, p. 259. ^ 

 Scales in 15 to 19 rows ; euboaudals 24-52. 11. coronella, p. 264. 



jS. Ventrals 150-235 j subeaudals 48-85 ; scales in 15 or 

 17 rows. 



* Rostral as deep as broad or a little broader than 



deep ; scales in 15 or 17 rows ; ventrals 150-191. 

 Froatal at least twice as long as broad .. 4. decemlineata,^.2Q0 

 Frontal not twice as long as broad 5. collaris, p. 260. 



** Rostral considerably broader than deep ; scales in 

 15 rows. 



t Frontal as long as the parietals ; ventrals 158-171 . 



6. fasciata, p. 262. 



ft Frontal much shorter than the parietals. 



Frontal once and two thirds as long as 



broad ; ventrals 186 7. angwstieeps, p. 262. 



Frontal not once and a half as long as 



broad : ventrals 159-187 8. rothi, p. 262. 



Frontal once and a half as long as broad, 



about once and a half as broad as the 



supraocular ; ventrals 194-216 9 persica, p. 263. 



Frontal once and a half as long as broad, 



nearly twice as broad as the supraocular ; 



ventrals 211-235 10. walten, p. 263. 



b. Seven upper labials ; portion of rostral visible from above 



measuring one half to two thirds its distance from the 

 frontal. 



II, Scales in 13 rows ; ventrals 126-137 ; subeaudals 

 37-46 12. taylori, p. 265. 



/3. Scales in 15 rows. 



* Body without black cross bars. 



Ventrals 145-163 13. episeopa, p. 265. 



Ventrals 183 14. torquata, p. 266. 



»* 



Body with black cross bars. 



Ventrals 158-167 ; subeaudals 50-52 .... 15. isozona, p. 266. 

 Ventrals 147-168; subeaudals P4-44 16. occipitalis, p. 266. 



